Factors Affecting Pregnancy Success in the Bitch Following Transcervical Insemination.

Endoscopic-assisted transcervical inseminations (TCIs) have become increasingly popular. The aim of this retrospective clinical study was to evaluate data from the TCIs performed at our facility. We evaluated data from January 2018 through December 2021. This included 137 cases with fresh, 67 cases chilled, and 63 cases using frozen-thawed semen. All bitches underwent breeding management to determine the ideal breeding period. All semen samples were evaluated for total number of sperm, total motility, and progressive motility. Pregnancy was determined by B-mode ultrasonography about 4 weeks after the breeding. Litter size was determined by radiographs performed around the last week of gestation. The pregnancy rate was 83.21% for fresh, 67.16% for chilled, and 66.67% for frozen-thawed semen. There was a significant difference in litter size between fresh semen (6.82 puppies per litter) and both chilled (5.21 puppies per litter) and frozen-thawed (4.59 puppies per litter) semen (P < .05). There was no significant difference in litter size between chilled and frozen-thawed semen. There was no difference in pregnancy rates between clinicians performing the inseminations. Pregnancy rate was not different when sedation was used for the insemination (66.67%) compared to when sedation was not used (74.84%; P > .05). Performing 2 TCIs during the fertile period, regardless of the semen type, resulted in an increase of 6.6% in pregnancy rate (P > .05) and an increase of 0.7 puppies per litter, on average (P > .05). These results can be used to help guide recommendations for breeding clients on the best options to increase both pregnancy rate and litter size for their breeding.

Evaluation of Biofilm Production by Escherichia coli Isolated From Clinical Cases of Canine Pyometra.

Many Escherichia coli (E. coli) strains produce biofilm that confers antimicrobial resistance. However, studies of biofilm production by E. coli from canine pyometra are lacking. Objectives were to elucidate the role of biofilm production by E. coli in pyometra by: (1) assessing the ability of E. coli to produce biofilm in vitro, and (2) confirming biofilm in situ. Endometrial biopsies were obtained from bitches with pyometra and preserved for microscopic analysis (n = 25). An endometrial swab was submitted for aerobic culture. Samples with confirmed E. coli were evaluated further for biofilm production in vitro and in vivo. Seventy percent of cases (16/23) resulted in pure growth of 1 or 2 E. coli strains, totaling 20 isolates. Fifteen isolates (15/20, 75%) had higher optical densities then negative controls (P < .05). On histopathology, all tissues exhibited endometrial inflammation and mucus was located within endometrial glands and occasionally overlying epithelium on 14 slides (14/16, 88%). Bacteria was noted in 50% of slides (8/16). During FISH acellular debris within the uterine lumen consistent with biofilm was noted on 94% of samples (15/16) and E coli was positively identified on all samples (15/15). Areas suggestive of the presence of biofilm were observed on all samples on scanning electron microscopy; but, bacteria consistent with E. coli were only visualized in 9 samples (9/16, 56%). In conclusion, we demonstrated that relevant strains of E. coli produce biofilm in vitro and in vivo, which may be considered in the development of new pyometra treatments aimed at disrupting these E. coli biofilm.

Technical Note: The use of iSperm technology for on-farm measurement of equine sperm motility and concentration.

The iSperm is a newly released semen analysis tool from Aidmics Biotechnology Co. LTD, which allows an iPad Mini to be transformed into a handheld microscope with objective semen analysis software for equine available through the Apple Store (version 4.5.2). The aim of this study was to compare iSperm values for sperm motility and sperm concentration to current acceptable methods for semen analysis and to determine the agreement with these methods using statistical methods. Two ejaculates from each of five Standardbred stallions were used to compare sperm motility (computer-assisted semen analysis [CASA] vs. iSperm) and concentration (NucleoCounter SP-100 [NC] vs. hemocytometer vs. iSperm). Data were analyzed by first testing for the differences between the means of each method using a linear mixed-effects model. The agreement between the two continuous measurements for each method was then investigated by computing Lin's concordance correlation coefficient (CCC), with a value of 1 indicating perfect agreement between methods. Results are reported as the CCC with the associated 95% confidence interval in parentheses. Means for both total motility (TM) and progressive motility (PM) were equal between CASA and iSperm values (P = 0.0741 and P = 0.725, respectively). However, means for all velocity measurements were significantly different between CASA and iSperm readings (P < 0.001). For concentration, means were equal between NC and iSperm values (P = 0.748) and for hemocytometer and iSperm values (P = 0.953). The CCC for TM was 0.871 (0.788, 0.923) and for PM was 0.916 (0.847, 0.955) indicating good agreement between methods. Low levels of agreement were observed for all velocity measurements. Finally, the CCC for concentration compared by iSperm and NC was 0.970 (0.949, 0.982) and for iSperm and hemocytometer it was 0.962 (0.934, 0.978), both close to the line of perfect concordance. Although more work is needed to improve the iSperm software for velocity measurements to be acceptable by research standards, in its present form the iSperm will introduce a low-cost and affordable method for on-farm semen analysis (TM, PM, concentration) for breeders and veterinarians. As a result, more farms will have access to accurate sperm analysis tools which will help to standardize semen processing procedures leading to better overall quality of semen used for artificial insemination.

Using Estrous Behavior to Time Initiation of Oxytocin Administration to Prolong Luteal Function in Mares.

The objective of this study was to use estrous behavior alone to determine the appropriate time for beginning an oxytocin treatment protocol for estrus suppression. We hypothesized that administration of oxytocin beginning 8 days after the onset of estrus will prolong the luteal phase in mares. Twenty-three light breed mares (aged 4-20 years) were exposed to a stallion and observed for signs of sexual receptivity. Mares not displaying signs received 250 µg of cloprostenol intramuscularly (IM) and were teased again 3-4 days later. On the day that estrous behavior was observed (Day 0), mares were randomly divided into two groups: oxytocin (n = 11): oxytocin (60 IU, IM) was administered once daily from Day 8-17; control (n = 12): did not receive treatment. Blood was collected from all mares every 4 days throughout Day 17, and every 7 days thereafter until Day 45. Serum progesterone concentrations >1.0 ng/mL were indicative of a functioning corpus luteum. Interestrus interval was defined as the period between Day 0 and the day when progesterone next reached <1.0 ng/mL. The average interestrus interval was higher for treated mares compared with control mares (32.4 ± 4.2 vs. 21.8 ± 1.5 days, respectively, P = .01). In the oxytocin group, the interestrus interval was longer than 31 days in 6 of 11 (54.5%) mares and up to 45 days in 5 of 11 mares (45.5%). We conclude that luteal maintenance beyond 30 days was attained by once-daily oxytocin administration beginning 8 days following behavioral estrus in a majority of mares.

Whelping and Dystocia: Maximizing Success of Medical Management.

Dystocia can be defined broadly as "difficult birth" or more specifically as difficulty in the bitch expelling the pups through the cervix, vagina, and vestibule. It is a fairly common emergency presented to the small animal practitioner with an incidence rate of approximately 5%. The incidence of dystocia is highest in toy and brachycephalic breeds, and occurs frequently in small litters (<3 pups) due to fetal oversize and delayed onset of labor. As duration of labor progresses, the mortality of the pups and even the bitch increases, with the highest number of stillborn pups occurring after 6 hours from the time of active parturition. Practitioners should understand the mechanism of normal parturition so that abnormalities can be readily identified and medical or surgical intervention performed in a safe and timely manner.